Consecutive weekly determinations of plasma retinol, alpha-tocopherol, retinol-binding protein, prealbumin, and zinc were performed on a group of 58 infants weighing less than 2000 g at birth in an intensive-care nursery. Data were classified by the feeding regimen of the preceding week: parenteral, premature formula, or own mother's milk. Mean plasma-retinol values were less than 20 mcg/dl, the lower limit of normal for adults, with the highest values in the formula-fed group. Retinol-binding protein and prealbumin values were lowest in the parenterally-fed group. Alpha-tocopherol concentrations were consistently maintained at levels higher than 500 mcg/dl only in infants fed their own mother's milk. Mean zinc concentrations above 70 mcg/dl, the lower limit of normal for adults, occurred only in parenterally fed infants. Doubling the recommended vitamin supplement in formula-fed infants did not produce a significant increase in plasma retinol or tocopherol.(author)